A microfabricated thickness shear mode electroacoustic resonator for the label-free detection of cardiac troponin in serum

Portable, and automated biosensors for the detection of cardiac biomarkers are important for the early diagnosis of acute myocardial infarction. We demonstrate a label-free microfabricated thickness shear mode electroacoustic device based on a ZnO piezoelectric film for the assay of cardiac biomarkers. This device combines an immunologic sensitive element with the resonator working in biological liquids. Based on the gravimetric mechanism, the immunoreaction between the target antigens and antibodies was detected by monitoring the frequency change in real-time to determine the concentration of cardiac troponin I. The device exhibits a linear response from 0.04 to 2 ng/ml and a low detection limit of 20 pg/ml in serum containing cardiac troponin I. The clinical samples collected from healthy controls and cardiac patients were directly used without any additional pre-treatment. The cardiac troponin concentrations measured by the proposed device shows good linear correlation and consistency compared with standard laboratory methods. The results indicate that the device can to be a feasible tool for sensitive, rapid, and miniaturized point-of-care analytical systems.